<%@ page contentType="image/jpeg" language="java"
	import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*"
	pageEncoding="utf-8"%>

<%!Color getRandColor(int fc, int bc) {
		Random random = new Random();
		if (fc > 255) {
			fc = 255;
		}
		if (bc < 255) {
			bc = 255;
		}
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);

		return new Color(r, g, b);
	}%>

<%
	//设置页面不缓存
	response.setHeader("Pragma", "no-cache");
	response.setHeader("Cache-Control", "no-catch");
	response.setDateHeader("Expires", 0);

	//在内存中创建图象
	int width = 60;
	int height = 20;
	BufferedImage image = new BufferedImage(width, height,
			BufferedImage.TYPE_INT_RGB);

	//创建图象
	Graphics g = image.getGraphics();
	//生成随机对象
	Random random = new Random();
	//设置背景色
	g.setColor(getRandColor(200, 250));
	g.fillRect(0, 0, width, height);
	//设置字体
	g.setFont(new Font("Tines Nev Roman", Font.PLAIN, 18));
	//随机产生干扰线
	g.setColor(getRandColor(160, 200));
	for (int i = 0; i < 255; i++) {
		int x = random.nextInt(width);
		int y = random.nextInt(height);
		int xl = random.nextInt(12);
		int yl = random.nextInt(12);
	}
	//随机产生认证码,4位数字
	String sRand = "";
	for (int i = 0; i < 4; i++) {
		String rand = String.valueOf(random.nextInt(10));
		sRand += rand;
		//将认证码显示到图象中
		g.setColor(new Color(20 + random.nextInt(110), 20 + random
				.nextInt(110), 20 + random.nextInt(110)));
		g.drawString(rand, 13 * i + 6, 16);
	}
	session.setAttribute("rCode", sRand);
	//图像生效
	g.dispose();
	//输出图像到页面
	ImageIO.write(image, "JPEG", response.getOutputStream());
	out.clear();
	out = pageContext.pushBody();
%>